A type of biomarkers for prostate cancer, called microRNAs (miRNAs), has a unique level in serum from cancer patients. Hence, detecting them will allow us to diagnose prostate cancer earlier. Currently, this type of biomarkers can only be detected by quantitative real-time polymerase chain reaction. However, this technique does not generate reproducible and reliable results when it is used to detect miRNAs at a low level. To be able to reliably quantify prostate cancer-specific miRNAs at a low level, we propose an ultrasensitive strategy that hires non-toxic virus nanoparticles for probing the miRNAs. This strategy is based on the fact that the virus nanoparticles can be engineered to become capable of emitting three different lights and form complex with nanoparticles for capturing the target miRNAs. It is thus possible to detect multiple target miRNAs in one platform because the virus nanoparticles can emit three different fluorescence lights for detecting three different target miRNAs when three different fluorescent molecules are presented on the surface of the virus nanoparticles. Our objective in this project is to develop the new strategy in order to quantify multiple prostate cancer miRNA biomarkers in serum samples, including three target miRNAs specific for the prostate cancer. We aim to achieve high sensitivity, accuracy, and reproducibility for detecting the prostate cancer biomarkers in serum. This project will develop a new facile method that can precisely detect the prostate cancer biomarkers and thus can be used for early prostate cancer diagnosis.